1. Field of the Invention
The present invention relates to a wrench with a simplified structure.
2. Description of the Related Art
U.S. Pat. No. 5,636,557 to Ma issued on Jun. 10, 1997 discloses a ratchet type ring spanner comprising a handle and a head portion extended from the handle. The head portion includes a circular peripheral wall defining a receiving compartment therein and a web area connected with the handle. A ratchet wheel is received in the compartment. An arcuate toothed member is mounted in a cavity defined in the web area and includes teeth on a side thereof for engaging with the teeth in an outer periphery of the ratchet wheel. A stop member is mounted in the cavity and includes an end bearing against the wall defining the cavity. A spring is mounted between the stop member and the toothed member to bias the toothed member away from the stop member. However, the wall defining the cavity must be processed to provide a depression for securely receiving a U-shape anchor of the stop member. The stop member and two wings on the stop member must be configured to correspond with the depression. These increase difficulty in manufacture, and there is a risk of disengagement of the anchor from the depression. The overall structure is complicated and the manufacture cost is relatively high. In operation, the wings of the stop member slide for a distance when the arcuate toothed member is driven by the ratchet wheel. It was, however, found that the wings tend to break, as the area of the wings subject to force is relatively small. In addition, the anchor tends to be carried away by the wings and is thus disengaged from the depression, which results in malfunction of the spanner.
It is the primary object of the present invention to provide an improved wrench with a simplified structure to thereby save the cost and time for assembly.
It is another object of the present invention to provide an improved wrench with a simplified structure, wherein malfunction resulting from sticking of the pawl to the drive member of the wrench is prevented.
A wrench in accordance with the present invention comprises:
a handle;
a head extended from the handle and including a compartment, a web being defined between the handle and the head, a cavity being defined in the web and communicated with the compartment, a transverse hole being defined in the web and including an inner end communicated with the cavity and an outer end communicated with outside;
a drive member rotatably mounted in the compartment and including a plurality of teeth on an outer periphery thereof;
a pawl slidably mounted in the cavity and including a toothed side, an attachment side, and a pressing side;
an anchor securely mounted in the transverse hole; and
an elastic element including a first end attached to the attachment side of the pawl and a second end attached to the anchor, the pawl being biased by the elastic element such that the toothed side of the pawl is biased to engage with the teeth of the drive member and that the pressing side of the pawl is biased to press against a wall defining the cavity.
The anchor includes an embossed end for frictional engagement with an inner periphery defining the transverse hole. The attachment side of the pawl includes a peg to which the first end of the elastic element is attached. In a case that the pawl is stuck to the drive member, the peg is impinged by another end of the anchor when the handle is turned in a free rotating direction and thus causes disengagement of the pawl from the drive member.
In an embodiment of the invention, the drive member includes a protruded portion on a top thereof. A ring cap is mounted around the protruded portion and includes an annular groove in an outer periphery thereof. An inner periphery defining the compartment of the head includes an upper portion with an annular groove. A C-clip is engaged in the annular groove of the protruded portion of the drive member and the annular groove of the head, thereby rotatably mounting the drive member in the compartment of the head. The inner periphery defining the compartment of the head includes an annular ledge projecting inward from a lower portion thereof. The drive member includes an inner periphery for engaging with a fastener. The inner periphery of the drive member includes a plurality of faces, each two adjacent faces having a concave portion therebetween.
In another embodiment of the invention, the anchor includes a flange on an outer periphery thereof and located in the cavity, and the second end of the elastic element is attached to the flange of the anchor.
In a further embodiment of the invention, the anchor includes a protrusion on an outer periphery thereof and located in the cavity, and the second end of the elastic element is attached to the protrusion of the anchor.
In still another embodiment. of the invention, the transverse hole is a screw hole, and the anchor includes a threaded section that is threadedly engaged in the screw hole.
Other objects, advantages, and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.